This invention relates to control devices for controlling the temperature, humidity, and/or other environmental conditions in an interior comfort space, and is more particularly concerned with an improvement to a wall thermostat to prevent inaccuracies and misoperation that may result from intrusion air which may enter the thermostat from a hollow wall on which the thermostat is mounted.
Wall thermostats are typically installed on an interior wall of a house or other building to control the operation of a furnace, air conditioner, heat pump, or other environmental control equipment. The thermostat is intended to monitor the temperature of the room or other interior comfort space continuously, and to adjust the operation of the associated environmental control equipment to keep the interior comfort space parameter (e.g., temperature) within some range (e.g., 68xc2x0 F., xc2x11.0xc2x0 F.). Other controls may be sensitive to other parameters, such as humidity or particulate level. The thermostat is connected to the furnace, air conditioner, heat pump or the like by means of a run of thermostat wires, which pass from the furnace control board up through spaces in the interior walls, and emerge at an opening in one of the walls, and this is the place the thermostat is to be mounted. An opening is provided in the back of the thermostat for the wires to pass through, so that the wires can be connected to appropriate contacts inside the thermostat housing.
In practice, the opening or penetration in the wall for the thermostat wires allows some intrusion air to enter the room, and this air passes through the thermostat opening, into the interior of the thermostat housing. As a result, the sensors inside the housing are influenced to a significant degree by intrusion air that comes through the hollow wall, and this air can be warmer or cooler than the rest of the air in the room. Even if a contractor plasters or caulks the wire opening during construction of the house, the plaster or caulk can eventually dry and crack, and permit intrusion air to enter the thermostat. As a result, the actual room air temperature (or humidity) can be outside the range set on the thermostat (or humidistat), and this can occur without any malfunction of either the thermostat or the environmental control equipment.
Accordingly, it is an object of the present invention to provide an improvement to a wall thermostat that overcomes the above-mentioned drawback(s) of the prior art.
It is another object to provide an effective solution to the above-mentioned problem, which solution is of a straightforward, one-piece design, and which is simple to install.
It is a more specific object to provide a barrier that diverts or blocks intrusion air from entering the thermostat or other similar control device.
In accordance with one aspect of the present invention, a thermostat arrangement that is adapted for mounting on a wall of a controlled space includes a thermostat having a front cover and a back plate adapted to be mounted on the interior wall. The back plate and the cover defining a cavity, and the temperature sensor and other control circuitry are contained within this cavity. The circuitry includes contacts which are adapted to receive two or more thermostat wires that protrude through a penetration in the wall. The back plate has mounting screw openings for mount the thermostat on said wall over said penetration, and also has a thermostat wire opening adapted to receive the two or more thermostat wires. As a means for blocking or redirecting intrusion air flow that may come out of the wall penetration and to avoid having the intrusion air enter the interior cavity of the thermostat, a resilient plug is fitted into said thermostat wire opening in the back plate. This plug may be a grommet of cross section to match that opening, and may be formed of a soft, resilient material, i.e., a rubbery material. The plug has a passage through which the thermostat wires are passed, with this passage closing over the thermostat wires.
Alternatively, a wall plate member may serve as a barrier to block intrusion air from the thermostat. In this case, the wall plate member is adapted to be installed between the wall and the back plate of the thermostat. The wall plate has a wire passage that is to be aligned with the wall penetration and through which said thermostat wires are passed. The passage closes over the thermostat wires. The wall plate member serves as a barrier to direct intrusion air that flows out the penetration away from the cavity of said thermostat.
In either case, any intrusion air ends up being mixed in with the room air, and does not pass directly into the thermostat. The thermostat then senses the room air parameters, e.g., temperature or humidity, much more accurately, and permits the furnace, air conditioner, heat pump, or other environmental control equipment to keep the interior room air within the comfort range that is set on the device.
The above and many other objects, features, and advantages of this invention will be more fully appreciated from the ensuing description of certain preferred embodiments, which are to be read in conjunction with the accompanying Drawing.